I'm making a 5 volt portable regulated power supply (using LM7805 regulator IC) for Arduino UNO. I'm planning to use a USB connector as its output socket, this way I can just plug and power the Arduino via USB. My problem is where do I connect the USB sockets's shield ? As far as I know it should be connected to the ground if it is a host device - can we consider the power supply as a host device?
Note: I've asked this question in arduino.stackexchange and advised to get in here.
I think most arduinos have the shield connected to USB ground anyways. The rules of the USB spec regarding power, grounding, isolation are often broken - either out of ignorance, cost or laziness. It only becomes a real issue when circuit ground and chassis ground are not the same, which can happen with mains-powered devices.
Quick note: if you are only going to use this for an arduino-application, you can just connect whatever voltage you are regulating directly to the arduino Vin pin. It has it's own local 5V regulator. Of course, using a USB cable might be easier.
